Umbraco is an ASP.NET content management system (CMS). Starting in version 8.0.0 and prior to versions 8.18.10, 10.8.1, and 12.3.4, a user enumeration attack is possible when SMTP is not set up correctly, but reset password is enabled. Versions 8.18.10, 10.8.1, and 12.3.4 contain a patch for this issue.